The function of adrenal cortical cAMP binding proteins in both the cytosol and plasma membranes of an energy dependent cAMP transport system in corticotropin mediated regulation of cholesterol metabolism and cytochrome P450scc activity will be studied. Hypophysectomized rats, bovine adrenal cortex, isolated bovine adrenal cortical cells and a Y-1 mouse adrenal tumor cell will be employed as experimental models in these studies. A corticotropin stimulated, cycloheximide inhibited, cytosolic cAMP binding protein and a cell surface cAMP receptor in adrenal cortical cells will be isolated and purified. Their potential function as regulatory subunits for protein kinases will be studied. Specific immunoprecipitation of 3H-leucine or 35S-methionine labelled binding proteins, their relationship to each other and to cAMP binding proteins in mitochondria will be studied. Cholesterol metabolism and cytochrome P450scc activity will be studied by dual wavelength and split beam difference spectroscopic analysis of high spin cholesterol bound cytochrome P450scc and by determining the rates of pregnenolone formation in intact mitochondria. Perturbation of the metabolism of these mitochondria will be accomplished by treating intact rats and cell cultures with corticotropin, cyclohexomide and aminoglutethimide and by additions of divalent ions, cAMP, theophylline, colchicine and IBMX to isolated mitochondria.